Mixing nozzle



2 Sheets-Sheet 1 igJ H. MARTIN ETAL MIXING NOZZLE June 7, 1966 FiledAug. 24, 1962 .ujil'a/z June 7, 1966 H. MARTIN ETAL MIXING NOZZLE 2Sheets-Sheet 2 Filed Aug. 24, 1962 ll 'lIiIlE-vllill United StatesPatent() 3,254,483 MlXING NOZZLE Herbert Martin and Karl Adolph,Esslingen (Neckar), Germany, assignors to J. Eberspacher, Esslingen(Neckar), Germany, a iirm of Germany Filed Aug. 24, 1962, Ser. No.219,255 Claims priority, application Germany, Aug. 24, 1961,

E 21,578 Claims. (Cl. 60-30) The present invention relates to a mixingnozzle, particularly for the induction of air into the exhaust pipe ofan internal combustion engine which for this purpose is provided with aconstriction similar to a Laval nozzle and with an orifice for thepassage of the air at the point of the smallest cross-sectional area ofthe constriction in the exhuast pipe.

Mixing nozzles of this type are being applied in exhaust pipes ofinternal combustion engines for mixing fresh air with the exhaust gases,for example, for the pur.- pose of cooling and afterburning the exhaustgases. There are also injectorlike mixing nozzles known in which theexhaust-gas pipe projects into a mixing cone.

The mixing ratio which is attainable with such mixing nozzles is onlyconstant Within a very limited range. If the cross-sectional yarea offlow of the air and the size of the nozzle constriction are adjustedrelative to each other in such a manner that a certain desired mixingratio will be attained at a low gas velocity, an entirely differentmixing ratio will occur at -a high gas velocity. For afterburning theexhaust gases it is, however, absolutely essential that thestoichiometric mixing ratio be constant under all operating conditionsin order to insure a complete combustion of these gases.

It is a well-known fact that. the exhaust gases of internal combustionengines also function as carriers of sound impulses. The fresh-airintake openings of the known nozzle structures have the disadvantagethat they may also act as outlets for noisy sound waves.

It is an object of the present invention to provide a mixing nozzlewhich permits the mixing ratio to be maintained constant under yanyoperating conditions. This object is attained according to the inventionby providing the mixing nozzle with a displacement element, a conicalpart of which projects into the constriction of the nozzle and which isadjustable by means of a control rod so as to be slidable in a directioncoaxial to the nozzle.

According to the invention, an annular orifice is formed between thedisplacement element and the wall of the mixing nozzle. By adjusting theconical displacement element, it is possible to increase or reduce thecross-sectional area of the nozzle orice. By employing a narrow annularorice, a low gas velocityl will be increased, while a high gas velocitywill be reduced if the size of the an# nular orifice is increased. Thus,the amount of fresh air drawn in will always be in the proper proportionto the particular operating conditions.

The displacement element of the mixing nozzle is made of theaerodynamically most suitable tear shape with its tip pointing in thedirection of flow. It also serves as a nonreilecting baille whichprevents a resonance of the pipes and an inductive transmission of thesound into the air intake opening.

Another object of the invention is to provide a mixing nozzle of themost suitable shape by arranging the nozzle itself between two elbows inthe exhaust pipe and by passing the control rod for the displacementelement through the walls of the bent elbows which intersect the axis ofthe mixing nozzle. By this construction it is possible to omit anysupporting means for the displacement element and the control rod at theinside of the exhaust pipe or the mixing nozzle and thus to avoid anyobstructions which might interfere with the ffree flow of the exhaustgases and the air through the pipe or pipes.

According to one embodiment of the invention, the double-elbow pipe ispreferably made of two molded shell sections which are provided withguide members for the control rod, for example, in the form of bushings,as integral parts thereof. These bushings may, of course, also beprovided with suitable packings for sealing purposes and forfacilitating the `sliding movement of the control rod therein.

Another feature of the invention consists in providing the elbow oradjacent parts of the exhaust pipe withsupporting means Afor the springor lever elements which are connected to and act upon the control rod.If the mixing nozzle according to the invention is employed for theexhaust pipe of an internal combustion engine, the control rod may bepositively connected to a control valve which is connected to the intakeline of the engine. The mixing ratio is then controlled in accordancewith the output of energy of the engine. If the engine is accelerated,the intake line contains a vacuum which is transmitted to the suctionchamber of the control valve, whereby a piston therein is retractedwhich is connected to the control rod which, in turn, retracts the`displacement element from the mixing nozzle so that large amounts ofexhaust gases can pass through the nozzle without being considerablyaccelerated. At lower speeds of the engine `and especially when theengine is idling, a compression spring in the control valve which isopposed to the suction therein acts upon the control rod so as toproject the displacement element more or less into the constriction ofthe mixing nozzle, whereby the cross-sectional size of the annular oriceis reduced and the exhaust gases passing through the nozzle areaccelerated to such an extent that a large amount of fresh air is drawnin than at the time when the nozzle orice is free of the displacementelement. In this manner it is possible to achieve what has often beentried unsuccessfully for the proper operation of exhaust gas cooling,neutralizing and afterburning device, namely, to adjust the mixing ratioin such a manner that the desired cooling, catalytic or afterburningeffect will be fully attained under any operating conditions of theengine.

According to `another embodiment of the invention, the adjustment of themixing nozzle may also be carried out automatically by mounting thedisplacement element in the mixing nozzle or in the mixing chamber infront of the open end of the exhaust pipe in such a manner that itpartly projects into this open end and is maintained by suitable meansin this position. Depending upon the prevailing amount of the exhaustgases and the resulting counterpressure, the displacement element isthen maintained in a certain opening position so that the annular gapwhich is formed between the displacement element and the wall of the endof the exhaust pipe is adjusted in proportion to the amounts of theexhaust gases. Therefore, if the pressure of the exhaust gases upon thedisplacement element increases, the latter is forced out of Vthe openend of the exhaust pipe.

The pressure at which the displacement element is partly inserted intothe open end of the exhaust pipe in the direction opposite to the ow ofthe exhaust gases may be produced by a spring which preferably has acurved characteristic.

3 A preferred embodiment of the invention consists in mounting thedisplacement element on a pivotable lever. The above-mentioned as wellas additional features and advantages of the present invention willbecome more y clearly apparent from the following detailed descriptionof several preferred embodiments thereof as illustrated in theaccompanying drawings, in which- FIGURE 1 shows a diagrammaticillustration of the mixing nozzle according to the invention as appliedto an exhaust pipe;

FIGURE 2 shows a diagrammatic illustration, partly in cross section, ofan exhaust gas neutralizing apparatus for an internal combustion engine;while FIGURE 3 shows a modification of the mixing nozzle according tothe invention.

Referring first to FIGURE 1 of the drawings, the exhaust line 1 ofengine 1a is provided with a U-shaped double-elbow pipe 2 which iscomposed of two shell sections which are connected to each other withina plane lying within the axis of the pipe. Pipe 2 is designed at 2a inthe form of a Laval nozzle. Shortly behind the narrowed point 2a of thisnozzle, air inlet openings 3 are provided. According to the invention, atear-shaped displacement element 4 is suspended at the center of thenozzle by means of a cable 5a which passes through the walls of the bentpipe to the outside and is secured at one end to a tension lever 6 whichby means of a tension spring 7 which is connected to the wall of pipe 2applies on cable 5a a tension in the direction of flow of the exhaustgases, as indicated by the arrows. The other end 5b of the cable isconnected to the accelerator of the internal combustion engine, notshown. When the accelerator is depressed, the displacement element 4 isdrawn out of the pipe constriction 2a with the result that thecross-sectional area of this constriction is increased because of therearwardly converging shapeof the displacement element 4. If the tensionon the accelerator or on the end 5b of the cable is decreased, thetension of spring 7 on lever 6 draws the displacement element 4 into theconstriction 2a and thereby reduces the crosssectional area of thenozzle orifice. This position of element 4 is shown in FIGURE 1 in fulllines, while its retracted position is indicated in dotted lines.

According to the modification of the invention as illustrated in FIGURE2, the displacement element 9 is disposed within an ejector 8 andconnected to a rod 10 which is positively connected to a piston rod 11aof a pressure valve 11. The combustion engine of a motor vehicle isindicated diagrammatically at 12, while 13 indicates an afterburningdevice fed with fuel and, if necessary, air through pipe 13a for heatingresidual combustible gases contained in the exhaust gases by means of anopen flame to a temperature sufficient for them to burn in; catalyticafterburning device 14. Within the ejector `8, the exhaust gas line 15is provided with a tubular enlargement 15a which contains thedisplacement element 9. The end of the exhaust gas line terminates intothe nozzle 8a of the ejector which is surrounded by an outer annularhousing 8b which is connected to the air intake pipe 16. Av part of thewall of this air intake pipe 16 is provided with perforations 16a andthis perforated part is surrounded by a sound absorber which is filledwith a sound-absorbent material. The suction chamber 11b of the pressurevalve 11 is connected by a pipe line 17 to the front part of the intakeline 18 of the combustion engine 112. If the engine is accelerated, avacuum is produced in the lower part of the intake line 18 andtransmitted to some extent t0 the suction chamber 11b, whereby piston11e` is drawn back against the action of spring 11d and the conical partof the displacement element 9 is thus retracted yfrom the constrictedend 15b of -the exhaust pipe. The operation of the ejector 8 isotherwise the same as that of the mixing nozzle according to FIGURE 1.

FIGURE 3 illustrates another modification of the invention, in which 19indicate the exhaust pipe of engine 19b and 20 the mixing nozzle whichat 20a surrounds the conical nozzlelike end 19a of the exhaust pipe andforms a mixing chamber with an air intake opening 21. The tear-shapeddisplacement element 22 is mounted on a lever 24 which, in turn, ismounted on a shaft 23, and its front part 22a projects in-to the openend 19a of the exhaust pipe. Under the tension of a spring 25 which isadjustab-ly connected to a bracket 26, lever 24 is normally pressedagainst a stop 27 yto maintain the displacement element 22 in a positionin which an annular gap a forms the smallest adjustable nozzle orifice.

In order to prevent the displacement element from producing an excessivecounterpressure in the mixing nozzle in the event that the guide membersof this element should becomeI wedged, which might result in damage tothe combustion engine, the invention further provides a bypass 28 whichmay 'be closed by a valve member 29 and connects a part of the exhaustpipe in front of the constriction with the part behind it. By means of apressureresponsible element 30, the valve member may be opened when acertain pressure in the exhaust pipe is reached.

In order to prevent oscillation of the displacement element which m-aybe caused by vibrations of the exhaust column, the invention furtherprovides the exhaust line with an acoustic suction resonator 31 which ispreferably tuned to a frequency range of 50 to 200 cycles. In thismanner it is possible to maintain the dynamic resistance of the mixingnozzle relatively small so that the fresh-air supply will not be reducedor shut off entirely because of a dynamic counterpressure.

Although our invention has been illustrated and described with referenceto the preferred embodiments thereof, we wish to have it understood thatit is in no way limited to the details of such embodiments, but iscapable of numerous modifications within the scope of the appendedclaims.

Having thus fully disclosed our invention, what we claim is:

1. In an internal combustion engine exhaust pipe, said pipe including afirst pipe section having a constricted portion terminating at itsnarrowest point in an opening directed downstreamward, a second pipesection having a part surrounded and spaced from said constrictedportion and a continuation of such part in a downstream direction, saidpart having at least one intake opening to the outside for the admisisonof air positioned laterally of said constricted portion, an elongatedsolid displacement element having its downstream end taperingsu'bstantially to a point and having a rounded upstream end, and meanssupporting said element adjacent and extending partly into theconstricted portion of the exhaust pipe for movement axially therein tovary the effective opening of the pipe.

2. A mixing nozzle as defined in claim 1, further comprising aneutralizing and afterburning device connected to said exhaust pipebehind said mixing nozzle.

3. A mixing nozzle as defined in claim 1, further comprising a soundabsorber connected to said air intake opening.

4. A mixing nozzle as'defined in claim 1, in which said displacementelement is disposed behind the open end of said constricted portion, andmeans for supporting and moving said element partly into and out of saidopen end, and means for limiting the extent to which said element may bemoved into said open end to define an annular nozzle orice of la minimumsize.

5. A mixing nozzle as defined in claim 4, yfurther comprising springmeans for normally maintaining said element in the position in whch itdefines said minimum orice size.

6. A mixing nozzle as defined in claim 4, in which said supporting meanscomprise a lever secured at one end to said element, means for pivotingsaid lever with said element about an axis laterally spaced from theaxis of said element, and spring means` acting upon said lever fornormally maintaining said element in the position in which it definessaid minimum orice size.

7. A mixing nozzle as dened in claim 4, in which said exhaust pipe isconnected by a by-pass to the mixing nozzle, a member for closing saidby-pass, and a pressure- Y responsive element within said exhaust pipefor controlling said closing member to open said by-pass when thepressure in the exhaust pipe reaches a predetermined value.

8. A mixing nozzle as defined in claim 4, in which an acoustic suctionresonator is provided Within said exhaust pipe, said resonator beingturned to a frequency range of 50 to 200 cycles.

9. In a device as claimed in claim 1, means operatively connected tosaid element resiliently urging it in a direc' tion to reduce theeiective opening.

10. In a device as claimed in claim 1, a control valve having a cylinderand a piston in .said cylinder operatively connected to said element,and a pipe connecting said cylinder to the intake line of the combustionengine.

References Cited by the Examiner UNITED STATES PATENTS Worthington 60-30Frazer 60--30 X Uhri et al. 60-30 X Gregg 230--112 Houdry. Bixler et al.60-29 X Tryhorn et a1. 60-13 Houdry 60-30 Ridgway 60-30 Bozzola 60-13FOREGN PATENTS France.

SAMUEL LEVINE, Primary Examiner.

JULIUS E. WEST, Examiner.

20 N. E. ABRAMS, A. S. ROSEN, Assistant Examiners.

1. IN AN INTERNAL COMBUSTION ENGINE EXHAUST PIPE, SAID PIPE INCLUDING AFIRST PIPE SECTION HAVING A CONSTRICTED PORTION TERMINATING AT ITSNARROWEST POINT IN AN OPENING DIRECTED DOWNSTREAMWARD, A SECOND PIPESECTION HAVING A PART SURROUNDED AND SPACED FROM SAID CONSTRICTEDPORTION AND A CONTINUATION OF SUCH PART IN A DOWNSTREAM DIRECTION, SAIDPART HAVING AT LEAST ONE INTAKE OPENING TO THE OUTSIDE FOR THE ADMISSIONOF AIR POSITIONED LATERALLY OF SAID CONSTRICTED PORTION, AN ELONGATEDSOLID DISPLACEMENT ELEMENT HAVING ITS DOWNSTREAM END TAPERINGSUBSTANTIALLY TO A POINT AND HAVING A ROUNDED UPSTREAM END, AND MEANSSUPPORTING SAID ELEMENT ADJACENT AND EXTENDING PARTLY INTO THECONSTRICTED PORTION OF THE EXHAUST PIPE FOR MOVEMENT AXIALLY THEREIN TOVARY THE EFFECTIVE OPENING OF THE PIPE.